The project is being done in three phases: (1) a serologic survey to identify the virus; (2) a cohort mortality study of liver cancer; and (3) a case-control study of liver cancer in relation to yellow fever vaccine lot number. The serologic study was completed and published in The New England Journal of Medicine in 1987. Three groups of about 200 each were compared: (1) men hospitalized in 1942 with post-vaccinal hepatitis; (2) men vaccinated from contaminated lots who had not become ill during the epidemic; and (3) men who had entered the Army only after the contaminated vaccine was withdrawn and replaced with vaccine free of human serum. The cohort mortality study involves the same comparison groups, each about 20,000 in size. With adjustment for age differences, mortality in the three groups is very similar and any excess liver cancer is small. Overall, the first two phases of the study indicate that the carrier rate was low and subsequent liver cancer rare among these .healthy young adults infected in 1942. The findings suggest that likelihood of liver cancer following hepatitis B virus infection depends on age at infection and is low for healthy young males. The case-control phase of the study yielded far less evidential material than had been hoped, largely because VA hospital diagnoses of liver cancer, as coded, too often could not be confirmed on review.